Abstract: In order to solve the technical difficulties in keeping stability of the filling system influenced by serious wear of pipeline，deep studies on the wear mechanism of backfilling pipeline were made by means of site investigation，theoretical analysis and digital simulation.The main wear forms of drilling pipe were determined，and the influence degree of different factors on pipeline wear was quantitatively analyzed by using the control variable method.A new method to calculate the height of slurry free fall area in vertical drilling pipe was given，the physical and mechanical model of impact force and wear loss from slurry at borehole entrance and bottom right-angle bend was set up，and the wear space at relevant wear position was determined.After discussion on the wear mechanism of pipeline via momentum，energy and slurry phase transition theory，the energy consumption formula of the pipeline wall per unit area was optimized，an air circulation flow concept for slurry free fall area in vertical drillhole was put forward，and a physical model about gas flow was established.

Key words: Transportation with gravity by pipelines, Wear mechanism, Backfill drill-hole, Numerical simulation